Two exciting new studies show that older men and women who have cycled for many years do not have the markers of aging found in non-exercising people (Aging Cell, March 8, 2018). Their muscle size and strength, amount of body fat, levels of hormones such as testosterone, and blood cholesterol levels were close to those of much younger people. Their maximal ability to take in and use oxygen was more like that of people in their twenties than in non-exercisers of their own age group. Incredibly, the cyclists' immunity did not show the deterioration that is expected with aging. These studies focused on cyclists, but similar results would probably be found with other types of sustained exercise.

The Studies
Researchers from London and Birmingham, England, studied the same groups of people with one study concentrating on muscles and the other on the immune system. The participants were 125 amateur cyclists (84 men, 41 women) aged 55-79 years. These were not elite athletes; to qualify for the study, the men had to be able to cycle at least 60 miles in 6.5 hours, and the women, 36 miles in 5.5 hours (a moderate pace of less than 10 miles per hour for the men and 6 1/2 miles per hour for the women). All of the participants had been cycling regularly for most of their adult lives, with an average of 26 years. These cyclists were compared to 75 healthy non-exercisers aged 57-80, and 55 younger non-exercisers aged 20-36. The authors excluded all people who were smokers or heavy drinkers or had high blood pressure or medical problems.

Amazing Benefits in Immunity
With aging, the thymus gland in the front of your upper chest shrinks and progressively loses some of its ability to make T-cells that help to protect you from developing cancers and infections. The most surprising news from this study is that the thymus glands of the older cyclists produced as many T-cells as those of the young people.

T-cells recognize foreign proteins on the surface of invading germs and cancers to tell your immunity to attack and kill these cells. They then stimulate your immune system to make antibodies to attach to and kill invading germs and cancer cells, and produce chemicals called cytokines that activate other T-cells to remove germs and cancer cells from your body. Other regulatory T-cells dampen down your immunity so that your immunity does not attack and destroy your own healthy cells.

Larger and Stronger Muscles and Better Use of Oxygen
The authors took muscle biopsies from the vastus lateralis muscle in the front of the cyclists' upper legs, the muscles strengthened most by cycling. The cyclists' muscles did not show the expected signs of aging:
• drop in muscle size,
• drop in mitochondrial protein content, and
• decrease in ability to take in and use oxygen.
Their muscles did show a decrease in capillary blood vessel density. The cyclists' maximal ability to take in and use oxygen, move air in their lungs, and develop muscle power (wattage) were like those of the much younger people.

Loss of Muscle Size and Strength with Aging
All people, even regular exercisers, can expect to lose muscle size and strength as they age. Researchers at the University of Guelph in Canada have offered a new explanation (Cell Reports, March 13, 2018). All muscle fibers contain many mitochondria, small furnaces that turn food into energy. However, this process of providing energy for muscle cells produces end products called Reactive Oxygen Species (ROS), also known as free radicals, that damage parts of muscle cells and are directly responsible for the loss of muscle fibers with aging. Muscles normally use another chemical called ADP to rid themselves of ROS. This study shows that everyone loses muscle fibers with aging because older muscles lose some of their ability to respond to ADP and as a result, they accumulate higher levels of ROS which cause the permanent destruction of muscle fibers with the resultant loss of muscle size and strength. However, the muscles of older regular exercisers are able to clear excess ROS far more efficiently than the muscles of non-exercisers, so they have less loss of size and strength.

Exercise Helps You to Live Longer, Even If You Already Have Heart Disease
Another new study reviewed 30 years of records of 3,307 adults who had had heart attacks or angina (pain from blocked arteries leading to the heart). Those who exercised at least a little bit were 36 percent less likely to die during the study period (J of the Am Coll of Card, March 2018;71(1)). Weight loss without exercising did not reduce their death rate. This study agrees with another study of more than 15,000 heart disease patients that also showed that exercise helps to prevent death in people who have already had heart attacks (J of the Am Coll of Card, October 2017;70(14:). Moderate activities can include walking, gardening, ballroom dancing, water aerobics or casual cycling. Vigorous exercise includes cycling faster than 10 miles an hour, jogging or lap swimming, according to the American Heart Association.

My Recommendations
These studies show that many of the accepted signs of aging come from lack of exercise, not just from getting older. Regular vigorous exercise as you age helps you to maintain healthful qualities of your younger days so that you will have a healthier and more active later life. Exercise helps to prevent disease and death, even if you have not been a life-long exerciser. Everyone should maintain a daily exercise program. It does not have to be intense to prolong your life. If you have existing health problems or questions, consult with your doctors about any limitations that may apply to you.

About the Author: Gabe Mirkin, MD

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D., brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. The Dr. Mirkin Show, his call-in show on fitness and health, was syndicated in more than 120 cities.
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